Pairot de Fontenay B1, Perron M2, Gendron C2,3, Langevin P2,4, Roy J-S1,2
1Center for Interdiscipinary Research in Rehabilitation and Social Integration, Quebec, Canada, 2Laval University, Rehabilitation, Quebec, Canada, 3Canadian Forces Health Services Group, Valcartier, Canada, 4Physio Interactive, Quebec, Canada
Background: Exercise therapy is widely recommended to reduce pain and disability in persons with non-specific low back pain (LBP), with emerging evidence suggesting a better effect for strengthening and core stabilization exercises. However, it is still unknown whether changes in muscle performance, as measured with endurance tests, are associated with improvements in functional performance. In addition, the responsiveness and the minimal clinical important difference (MCID) of trunk muscle endurance tests have yet to be defined.
Purpose:
1) to determine the responsiveness and MCID of common trunk muscles endurance tests and
2) to verify the relationships between changes in holding time of these tests and perceived functional improvement in persons with LBP.
Methods: Soldiers with sub-acute LBP and a minimal score of 17% on the Oswestry Disability Index were eligible for this study. We excluded candidates with previous spine surgery, lumbar spine injection in the past two weeks, signs of upper motor neuron lesions, serious medical conditions and unavailability to participate in an 6-week exercise program. Endurance time of four isometric trunk muscle tests (right and left side bridge tests, trunk flexor endurance test, Biering-Sørensen test) was measured at baseline and at the end of participation to an exercise program. The multi-station full-body supervised exercise program was composed of seven thematic stations, each including strengthening, stabilisation and functional exercises of increasing difficulty. Participants rated their perceived change at the end of the program with a global rating of change (GRC) scale. We calculated the standardized response mean (SRM) to determine the responsiveness of endurance tests. We calculated the sensitivity, specificity and area under the ROC curve (AUC) to determine the MCID (threshold ≥ 4 on the GRC scale for responders and ≤ 3 for non-responders). We established correlations between GRC score and endurance time of the trunk muscles by calculating Pearson correlation coefficients.
Results: Eighty-four soldiers participated in this study. The SRM for the participants who were at least moderately improved (GRC≥4, n=55) were moderate for both the left- (0.55, 95%CI: 0.19 - 0.92) and right-side bridge tests (0.75, 95%CI: 0.32 - 1.19), and large for both the trunk flexor endurance test (0.94, 95% IC: 0.43 - 1.44) and the Biering-Sørensen test (1.02, 95%CI: 0.48 - 1.57). We could not determine any MCID, as there was no point of optimal trade-off between sensitivity and specificity. The AUC ranged from 57 to 67%. Correlations between improvement in the trunk flexor endurance test, the Biering-Sørensen test and the GRC score were low (r=0.28, p=0.015; r=0.20, p=0.038, respectively) while improvements in side-bridge tests and the GRC were not significantly correlated.
Conclusion(s): Responsiveness of trunk muscle endurance tests was moderate to large. However, the capacity of these tests to discriminate between different levels of improvement (MCID) was very low. Furthermore, an increase in endurance time seems very weakly related to the perceived global functional improvement.
Implications: The use of trunk muscle endurance tests in the clinic to set patients' goals and to determine functional improvement in persons with LPB should be made with caution.
Keywords: Low Back Pain, endurance tests, metrological properties
Funding acknowledgements: This study was supported by the Ordre professionnel de la
physiothérapie du Québec and Quebec Rehabilitation Research Network.
Purpose:
1) to determine the responsiveness and MCID of common trunk muscles endurance tests and
2) to verify the relationships between changes in holding time of these tests and perceived functional improvement in persons with LBP.
Methods: Soldiers with sub-acute LBP and a minimal score of 17% on the Oswestry Disability Index were eligible for this study. We excluded candidates with previous spine surgery, lumbar spine injection in the past two weeks, signs of upper motor neuron lesions, serious medical conditions and unavailability to participate in an 6-week exercise program. Endurance time of four isometric trunk muscle tests (right and left side bridge tests, trunk flexor endurance test, Biering-Sørensen test) was measured at baseline and at the end of participation to an exercise program. The multi-station full-body supervised exercise program was composed of seven thematic stations, each including strengthening, stabilisation and functional exercises of increasing difficulty. Participants rated their perceived change at the end of the program with a global rating of change (GRC) scale. We calculated the standardized response mean (SRM) to determine the responsiveness of endurance tests. We calculated the sensitivity, specificity and area under the ROC curve (AUC) to determine the MCID (threshold ≥ 4 on the GRC scale for responders and ≤ 3 for non-responders). We established correlations between GRC score and endurance time of the trunk muscles by calculating Pearson correlation coefficients.
Results: Eighty-four soldiers participated in this study. The SRM for the participants who were at least moderately improved (GRC≥4, n=55) were moderate for both the left- (0.55, 95%CI: 0.19 - 0.92) and right-side bridge tests (0.75, 95%CI: 0.32 - 1.19), and large for both the trunk flexor endurance test (0.94, 95% IC: 0.43 - 1.44) and the Biering-Sørensen test (1.02, 95%CI: 0.48 - 1.57). We could not determine any MCID, as there was no point of optimal trade-off between sensitivity and specificity. The AUC ranged from 57 to 67%. Correlations between improvement in the trunk flexor endurance test, the Biering-Sørensen test and the GRC score were low (r=0.28, p=0.015; r=0.20, p=0.038, respectively) while improvements in side-bridge tests and the GRC were not significantly correlated.
Conclusion(s): Responsiveness of trunk muscle endurance tests was moderate to large. However, the capacity of these tests to discriminate between different levels of improvement (MCID) was very low. Furthermore, an increase in endurance time seems very weakly related to the perceived global functional improvement.
Implications: The use of trunk muscle endurance tests in the clinic to set patients' goals and to determine functional improvement in persons with LPB should be made with caution.
Keywords: Low Back Pain, endurance tests, metrological properties
Funding acknowledgements: This study was supported by the Ordre professionnel de la
physiothérapie du Québec and Quebec Rehabilitation Research Network.
Topic: Musculoskeletal: spine; Outcome measurement
Ethics approval required: Yes
Institution: CIUSSS de la Capitale- Nationale (Quebec Rehabilitation Institute)
Ethics committee: CIUSSS de la Capitale-Nationale research ethics commitee
Ethics number: 2013-302
All authors, affiliations and abstracts have been published as submitted.
